Torque disconnect mechanism

ABSTRACT

A torque disconnect mechanism controls transmission of torque from a first shaft to a second shaft in a transmission. The mechanism includes a housing which rotatably supports the first and second shafts, and which has an opening formed therein. A coupling member is movable from an engaged position wherein the coupling member couples the first shaft with the second shaft to a disengaged position wherein the first and second shafts are uncoupled from each other. A plug member is mountable in the opening and is engagable with the coupling member. The plug member is movable from a first position holding the coupling member in its engaged position to a second position holding the coupling member in its disengaged position.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a mechanism for coupling anduncoupling components of a transmission and controlling the transmissionof torque therebetween.

[0002] When servicing or diagnosing a transmission it is desirable todisconnect the transmission output shaft and prevent torque from beingtransmitted to the output shaft. A transmission on a production JohnDeere tractor includes a sliding collar which couples and uncouples apair of gears which transmit torque from a planetary transmission shaftto the transmission output shaft. A pivoting shift fork is coupledbetween the collar and an arm which extends outside the transmission. Along release rod extends to the rear of the tractor and engages aspring-loaded bracket. Because of tolerance stackup it is possible forthe fork to rub on the collar during normal operation, and the partstake up space at the rear of the tractor, yet these parts are rarelyused.

SUMMARY

[0003] Accordingly, an object of this invention is to provide a simplertorque disconnect device with fewer parts.

[0004] These and other objects are achieved by the present invention,wherein a torque disconnect mechanism controls transmission of torquefrom a first shaft to a second shaft in a transmission. The torquedisconnect mechanism includes a drive gear rotatably mounted on thefirst shaft. The drive gear has a first set of drive splines whichmeshingly engage corresponding splines on the second shaft, and a secondset of drive splines. A hub gear is fixed for rotation with the firstshaft and includes a set of hub splines. A coupling member is engagablewith the drive gear and with the hub gear, and is movable from anengaged position wherein the coupling member couples the hub splineswith the second set of drive splines to a disengaged position whereinthe hub splines are uncoupled from the second set of drive splines. Aplug member is mounted in a housing opening and is engagable with thecoupling member. The plug member is movable from a first positionholding the coupling member in its engaged position to a second positionholding the coupling member in its disengaged position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005]FIG. 1 is a simplified sectional view of the present invention ina torque transmitting position;

[0006]FIG. 2 is a view similar to FIG. 1, but showing the presentinvention in a torque-disconnect position;

[0007]FIG. 3 is a partial sectional view of the collar of FIG. 1;

[0008]FIG. 4 is a perspective view of the collar of FIG. 1;

[0009]FIG. 5 is a perspective view of the plug of FIG. 1;

[0010]FIG. 6 is a top view of the plug of FIG. 1;

[0011]FIG. 7 is a sectional view along lines 7-7 of FIG. 6; and

[0012]FIG. 8 is a sectional view along lines 8-8 of FIG. 6.

DETAILED DESCRIPTION

[0013]FIG. 1 shows a portion of a transmission 10 which includes ahousing 12 which rotatably supports a shaft 14 and a shaft 16. Shaft 14may be a planetary output shaft and shaft 16 may be a transmissionoutput shaft. Shaft 14 is supported by bearings 18 and 20, while shaft16 is supported by bearings 22 and 24. A hollow hub gear 26 is mountedon shaft 14. Gear 26 includes inner splines 28 which engage outersplines 30 on the shaft 14. Gear 26 also includes outer splines 32.

[0014] A drive gear 40 is rotatably mounted on a portion of the hub gear26. Drive gear 40 includes a large diameter part 42 on which are formedsplines 44. Splines 44 engage corresponding splines 46 on shaft 16.Drive gear 40 also includes a smaller diameter part 48 on which areformed splines 50 which are axially adjacent to splines 32 of hub gear26.

[0015] An annular collar 52 is mounted over the splines 50 and 32. Asbest seen in FIG. 3, collar 52 has a generally cylindrical body with apair of axially spaced apart sets of splines 54 and 56 separated by anradially inwardly opening annular groove 58. The outer surface of thecollar 52 forms a pair of lands 60 and 62 separated by an outer annulargroove 64. As best seen in FIG. 4, a plurality of teeth 63 may be formedon land 62 for use with a standard magnetic speed sensor (not shown).

[0016] Referring to FIGS. 1 and 2, housing 12 has an opening 70 formedtherein. A service disconnect plug 72 is removably mounted in theopening 70. As best seen in FIGS. 4-7, plug 72 has a generallycylindrical head portion 74 in which are formed a pair grooves 76 and 78for receiving O-ring seals. A central cylindrical shaft 80 projectsaxially away from head 74. A tab 82 projects axially away from one sideof the end surface of shaft 80. A threaded central blind bore 84 extendsinto an outer surface of the head 74 for receiving a threaded tool (notshown) for use in manipulating the plug 72. As best seen in FIG. 5,textual instructional labels may be printed on the end surface of thehead 74 to guide an operator in orienting the plug 72 in the opening 70.As best seen in FIGS. 4, 5 and 7, a pair of partial circular cutouts 86and 88 are formed in a radial outer peripheral surface of the head 74.As best seen in FIG. 6, the tab 82 is offset from, or positionedentirely on one side of a central axis 90 of the head 74.

[0017] With the plug 72 oriented in opening 70 as shown in FIG. 1, thetab 82 extends from the left side of the shaft 80 into groove 64 of thecollar 52. This holds collar 52 in its engaged position wherein splines54 and 56 are in meshing engagement with splines 50 and 32,respectively, and torque can be transmitted from shaft 14 to shaft 16.

[0018] To disengage shaft 14 from shaft 16, the plug 72 is removed fromopening 70 and a tool (not shown) is inserted through opening 70 andinto grove 64, and the tool is then manipulated to slide collar 52 tothe right into the disengaged position shown in FIG. 2. The plug 72 isthen preferably re-oriented so that the tab 82 is oriented to the right,and then plug 72 is re-inserted back into opening 70 so that tab 82 isreceived by groove 64. Tab 82 thereby holds collar 52 in its disengagedposition wherein splines 56 are uncoupled from splines 32 and torquecannot be transmitted from shaft 14 to shaft 16.

[0019] While the present invention has been described in conjunctionwith a specific embodiment, it is understood that many alternatives,modifications and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, this inventionis intended to embrace all such alternatives, modifications andvariations which fall within the spirit and scope of the claims.

We claim:
 1. A torque disconnect mechanism for controlling transmissionof torque from a first shaft to a second shaft in a transmission,comprising: a housing rotatably supporting the first and second shafts,the housing having an opening formed therein; a coupling member beingmovable from an engaged position wherein the coupling member couples thefirst shaft with the second shaft to a disengaged position wherein thefirst and second shafts are uncoupled from each other; and a plug membermountable in the opening and engagable with the coupling member, theplug member being movable from a first position holding the couplingmember in its engaged position to a second position holding the couplingmember in its disengaged position.
 2. The torque disconnect mechanism ofclaim 1, wherein: the coupling member is a hollow annular member whichreceives one of the shafts.
 3. The torque disconnect mechanism of claim1, wherein: the plug member comprises a cylindrical head receivable inthe opening, and a tab projecting from the head, the tab being engagablewith the coupling member, and the tab being offset from a central axisof the head.
 4. The torque disconnect mechanism of claim 3, wherein: adrive gear is rotatably mounted on the first shaft, the drive gearhaving a first set of drive splines which meshingly engage correspondingsplines on the second shaft, and having a second set of drive splines; ahub gear is mounted on the first shaft and is fixed for rotation withthe first shaft, the hub gear having a set of hub splines formedthereon; and the coupling member comprises an annular collar engagablewith the drive gear and with the hub gear, the collar having an annulargroove which receives the tab of the plug member.
 5. The torquedisconnect mechanism of claim 3, wherein: a drive gear is rotatablymounted on the first shaft, the drive gear having a first set of drivesplines which meshingly engage corresponding splines on the secondshaft, and having a second set of drive splines; a hub gear is mountedon the first shaft and is fixed for rotation with the first shaft, thehub gear having a set of hub splines formed thereon; and the couplingmember comprises a hollow annular member having a first set of innersplines and a second set of inner splines spaced axially away from thefirst set of inner splines, an annular groove between the first andsecond set of inner splines, an outer surface of the annular memberforming a first land and a second land separated by radially outwardlyopening annular groove, the first set of inner splines meshing with thesecond set of drive splines, and the second set of inner splines beingselectively meshable with the hub splines.
 6. The torque disconnectmechanism of claim 1, wherein: a drive gear is rotatably mounted on thefirst shaft, the drive gear having a first set of drive splines whichmeshingly engage corresponding splines on the second shaft, and having asecond set of drive splines; a hub gear is mounted on the first shaftand is fixed for rotation with the first shaft, the hub gear having aset of hub splines formed thereon; and the coupling member comprises anannular collar engagable with the drive gear and selectively engagablewith the hub gear, the collar having an annular groove which receivesthe plug member.
 7. The torque disconnect mechanism of claim 1, wherein:the plug includes a tool-receiving aperture in an outer surface thereof.8. A torque disconnect mechanism for controlling transmission of torquefrom a first shaft to a second shaft in a transmission, comprising: adrive gear rotatably mounted on the first shaft and having a first setof drive splines which meshingly engage corresponding splines on thesecond shaft, and having a second set of drive splines; a hub gear fixedfor rotation with the first shaft and having a set of hub splines formedthereon; a coupling member engagable with the drive gear and with thehub gear, the coupling member being movable from an engaged positionwherein the coupling member couples the hub splines with the second setof drive splines to a disengaged position wherein the hub splines areuncoupled from the second set of drive splines; and a plug memberengagable with the coupling member, the plug member being movable from afirst position holding the coupling member in its engaged position to asecond position holding the coupling member in its disengaged position.9. The torque disconnect mechanism of claim 8, wherein: the couplingmember comprises a hollow annular member having a first set of innersplines and a second set of inner splines spaced axially away from thefirst set of inner splines, an outer surface of the annular memberforming a first land and a second land separated by radially outwardlyopening annular groove, the first set of inner splines meshing with thesecond set of drive splines, and the second set of inner splines beingselectively meshable with the hub splines.
 10. The torque disconnectmechanism of claim 9, wherein: the coupling member includes a radiallyinwardly opening annular groove between the first and second set ofinner splines, said annular groove receiving the second set of splinesof the drive gear when the coupling member is in its disengagedposition.
 11. The torque disconnect mechanism of claim 8, wherein: theplug includes a tool-receiving aperture in an outer surface thereof.